# Thermodynamics Properties of Leucine and Isoleucine Peptides in Water

## TL;DR

This study examines how the thermodynamic properties of leucine and isoleucine peptides change in water as their chain length increases.

## Contribution

The study provides new insights into how solvation free energy, hydrogen bonds, and solvent accessible surface area change with chain length in leucine and isoleucine peptides.

## Key findings

- Solvation free energy increases with the chain length of leucine and isoleucine peptides.
- Hydrogen bond formation and solvent accessible surface area also increase with longer peptide chains.
- The TIP3P water model and OPLS-AA force field were effective in modeling these thermodynamic behaviors.

## Abstract

Thermodynamic properties of amino acids explore the ideas about the energetic contribution in biomolecular interfaces. In our work, we have estimated the solvation free energy of leucine and isoleucine peptides with the variation of chain length or residues of different monomer units (n=1, 2, 4, 8 & 16) using molecular dynamic simulation. We modeled our system using OPLS‐AA force field and TIP3P water model at 310 K temperature. Solvation free energy of both leucine and isoleucine peptides increases with increase in chain length, which have been reported by using TI, TI‐CUBIC and BAR methods. The increase in solvation free energy with increase in chain length of both peptides is also supported by the increase in hydrogen bond and solvent accessible surface area (SASA) with the number of residues.

This article focuses on the thermodynamic properties of leucine and isoleucine peptides in water focusing on solvation free energy, SASA, and hydrogen bonds for TIP3P water model at 310 K temperature. This provides new insights into the interaction of these amino acids in aqueous environments, highlighting key factors influencing their stability and molecular characteristics. It is seen that the solvation free energy increases with increase in chain length of the peptide.